Here is the full list of all 66 Torchlight achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Defeat Ordrak on Very Hard Hardcore
Kill 25 champion trolls
Complete 50 Hatch Quests
Retire over 300 levels worth of characters
Defeat Ordrak on Hard Hardcore
Sell 10,000 items to vendors
Defeat Ordrak on Normal Hardcore
Kill 50,000 monsters
Drink 5,000 potions
Retire two characters
10 mods used at the same time
Defeat Ordrak with no deaths
Defeat Ordrak on Easy Hardcore
Retire a character
Complete 200 Quests
Reach level 100
Catch 1000 fish
Smash 1500 Breakables
Die 500 times
Reach the 50th floor of a dungeon
Achieve player level 100
Gamble 100 times
Beat the game with all three classes
Gamble 50 times
Suffer 20 disenchants from the enchanter
Achieve maximum fame
Achieve player level 65
Complete 25 Gar Quests
Permanently transform your pet
Have an item disenchanted on the first enchantment attempt
Do at least 10,000 damage to an enemy in a single strike
Collect 250,000 gold
Gamble 20 times
Defeat Ordrak in 8 hours or less
Defeat Ordrak in less than 5 hours
Successfully enchant one item 10 times
Successfully enchant one item 5 times
Defeat Ordrak on Easy or Normal
Defeat Ordrak on Hard
Defeat Ordrak on Very Hard
Defeat Alric
Gamble a unique item
Have 100,000 gold in your inventory
Defeat Medea
Kill 5000 Monsters
Defeat Krag
Successfully create 25 items using the transmuter
Defeat the Ember Colossus
Use 50 potions on your pet
Defeat the Root Golem
Take 25,000 steps
Pull 100 levers
Equip a spell on your pet
Defeat the Overseer
5 mods installed at the same time
Catch 100 fish
Transform your pet into a Mimic
Catch 50 fish
Defeat Brink
Blow 25 enemies to pieces with critical strikes
Fill your pet's inventory
Send your pet to town
Find the entrance to the mine
Change your pet by feeding it fish
Achieved enlightenment by speaking with the horse 100 times
1 game mod installed